The present invention relates to devices for laying down a continuous bead of weld overlay material in a selected pattern on a metal base. Devices within the scope of the present invention find particular application as semi-automatic and automatic welding machines used for overlay welding of new metal for the repair of oversize or worn bores, undersize trunnions and worn faces of mechanical equipment.
Devices within the scope of the present invention are designed principally for welding in an indexed repetitive pattern for example a helix, continuous spiral flat mode, or adjacent straight weld beads and at angles in an included range of a vertical to horizontal postion. Likewise, in addition to continuous welding, devices within the scope of the present invention can be adapted to perform incremental welding.
While the method and apparatus of the present invention are useful in many applications, the method and apparatus is particularly useful in the repair of enlarged interal bores or worn outer cylindrical surfaces. For example, in the repair of oversize bores where the bore receives a pin and acts as a pivot, the bore wears internally so the diameter becomes too large to permit satisfactory operation of the equipment. Another example is the inside and outside diameters of cylinder walls and trunnions on hydraulic and other mechanical devices where a piston, cylinder or shaft causes wear. In such instances the prior art has generally utilized sleeving as a means of repair. However it has been found that in many instances the sleeves "coin" and fall out of the bore after a short period of reuse.
Additionally the present invention provides method and apparatus useful in overlay welding construction, for example where a carbon steel base is overlaid with another metal such as stainless steel.
The present invention provides means to replace the worn metal with metal of characteristics at least equal to the original and permits remachining of the bore substantially as it was originally.
No prior art device is known for accomplishing the objectives of the present invention for repairing bores, trunnions or/and faces, by overlay welding in a semi-automatic or automatic mode on a continuous or incremental basis in the same means as the present invention.
With the exception of robotic controlled welding (where no prior art device is known which provides means for a buildup of metal in long length bores) the prior art provides a fixed welding head and the use of rotatable welding positioners and manipulators utilized as a cooperative pairs where the devices are used in tandem to position and move the element to be welded as opposed to rotation of the welding heads as provided by device in accordance with the present invention. In such prior art arrangements the positioner holds and turns the work piece while the manipulator or welder holds and manipulates the welding torch. Present day equipment is limited by the size of the part being welded and requires parts that can be readily clamped and centered on a positioner. If the part is too large for the positioner a different arrangement must be utilized.
Additional problems are encountered in the prior art, in that balancing the work piece on the weld positioner is necessary to ensure proper welding speed and the overhanging weight of the part must not exceed the capacity of the positioner.
No prior art device is known which permits continuous repetitive indexed feed of an incremental welding bead inside or outside of cylindrical shapes or continuous spiral feed welding on flat surface, while the work piece doesn't move. Prior art equipment further cannot be used to perform incremental welding of bores that are unevenly enlarged or out of round due to excessive wear.
Two known prior art devices illustrated in FIG. 1A and 1B the accompanying drawings are manufactured respectively by the C. C. Peck Company of Cleveland, Ohio and the Bancroft Corporation of Waukesha, Wis., to provide means for welding but both have the welding head and the part exposed at an angle with respect to one another and the welding heads cannot be rotated through more than 360.degree. nor can the heads be laterally advanced and retracted.
The prior art further includes various patents which relate to rotatable type welding equipment but none of which teach the features of the present invention. The references include Valentine, U.S. Pat. No. 3,913,820; Yasenchak, U.S. Pat. No. 3,665,148; Mikulak, U.S. Pat. No. 2,749,421; Cooper, U.S. Pat. No. 3,543,989; Kemsure, U.S. Pat. No 4,131,783; and Massakihano, U.S. Pat. No. 3,709,423.